Lightweight Active Anti-Icing/De-Icing for Remotely Piloted Aircraft (RPA)

ABSTRACT: During Phase I, FBS, Inc. developed and demonstrated a light-weight, low-power, non-thermal, ultrasound-based ice protection system for RPA wing leading edges and other metallic and composite components requiring ice protection. Low-profile, light-weight, low-power ultrasonic actuators are strategically placed inside the wing section and activated when icing conditions are encountered to perform de-icing of the wing leading edge. Ultrasonic de-icing is achieved by driving the actuators to create ultrasonic shear stresses at the substrate/ice interface such that the ultrasonic stresses are greater than the adhesion strength of the ice in order to promote ice delamination and cracking. FBS expertise is applied in optimizing actuator design and frequency selection, and newly-developed phasing technologies are used to achieve dynamic focusing across key regions of the structure of concern. The system was successfully demonstrated on a composite RPA airfoil section in freezer ice conditions during Phase I. During Phase II, several icephobic coatings that showed potential will be further analyzed for use in conjunction with the ultrasonic de-icing system, and full-scale RPA wing section testing will be performed in a realistic icing wind tunnel. Additional system development will include hardware and software improvements, as well as considerations for electronics miniaturization. BENEFIT: The proposed technology has the potential to revolutionize ice protection systems for aircraft. Some of the popular conventional ice protection systems include icephobic coatings, electro-thermal systems, and pneumatic boot systems. Electro-thermal systems are heavy, have demanding power requirements, are sometimes unreliable, and can cause damage to composite materials from overheating. Pneumatic systems are also heavy and sometime unreliable. If a coating was available that could withstand flight environments; it could be used in conjunction with the ultrasound to further reduce the size, weight, and effectiveness of the ultrasonic de-icing system. The proposed ultrasonic approach is unique in that discrete repairable actuators provide low-power non-thermal de-icing without damaging the composite structure. The power requirements for the ultrasonic system are orders of magnitude lower than that of electro-thermal systems. The ultrasonic actuators used for ice protection also have great potential to be utilized in the future as ultrasonic guided wave sensors to monitor structural health and even sense ice accretion for efficient driving of the ice protection mode of operation.